This Universe is Broken
by Doomed-Kelpie
Summary: What happens when Underfell Sans remembers what the original universe was like? (Underfell AU) (TRIGGER WARNING: ATTEMPTED SUICIDE)


**This Universe is Broken**

 _So, I decided to write an Undertale fanfiction that isn't my weird Chowdertale AU. However, this is still going to be an AU… Underfell!_

 _(TRIGGER WARNINGS: ATTEMPTED SUICIDE)_

XXX

"SANS! WHERE ARE YOU, YOU MISERABLE BAG OF BONES!" Papyrus screamed as he searched for his older brother, who, once again, had abandoned his sentry post.

The tall skeleton growled, seething with anger as his search continued on. The skeleton clearly wasn't in Snowdin anymore, but that left the rest of the Underground to search in.

"I swear, when I find that imbecile….," Papyrus threatened vaguely. "If he wasn't my brother…"

Papyrus thought to himself that Sans better be in Waterfall so that he wouldn't have to waste any more time on his brother's stupidity than he had to.

It took much more time searching in the dark than Papyrus wanted to spend, but he eventually found Sans huddled behind a pile of garbage in the dump.

"SANS!" he shouted angrily, paying no mind to the state his brother was in.

He grabbed Sans roughly and shoved him against the hard rock wall, knocking his brother's HP down to 0.5.

"HOW DARE YOU ABANDON YOUR POST AGAIN, AND THEN YOU MAKE ME WANDER THROUGH TRASH TO FIND YOU?!" Papyrus raged. "HOW MANY TIMES DO I HAVE TO PUNISH YOU BEFORE YOU UNDERSTAND YOUR PLACE?! ARE YOU REALLY-!"

Papyrus then cut himself off as his mind finally registered what his brother looked like. His eyes were pitch black, which wasn't strange by itself, but Sans had always glared back at his brother, eye glowing, when he scolded him. The smaller skeleton was visibly shaking, and tears were streaming down his bony cheeks, which Papyrus hadn't seen since they were young children. Most disturbingly, Sans was mumbling something so rapidly that it was incoherent. Surprised, Papyrus dropped his brother onto the flooded floor.

"Sans, cease your mumbling and listen to me when I'm speaking to you!" Papyrus ordered sternly, although his voice had a bit less anger in it than a second before.

When Sans still didn't seem to register that his brother was even there, Papyrus grabbed his shoulders and shook him until he started to struggle against him.

"Sans, what in the world has gotten into you?!" Papyrus questioned, making his voice angry to hide any bit of worry he might have felt.

Sans looked up at him, stopping his mumbling, before speaking directly to Papyrus.

"something happened. none of this is right. something happened, and now the entire universe is messed up. this isn't what everything is supposed to be. this is all wrong…," Sans told him, his voice shaky.

"Sans, what in the world are you babbling about?" Papyrus asked.

Sans looked away.

"this universe is a glitch," he said in a way that made it so that Papyrus couldn't tell if it was an answer or further nonsense.

Papyrus sighed, annoyed at the perplexing situation.

"everything is wrong. monsters weren't like this. something happened to the code…," Sans continued.

Papyrus's minimal patience had worn thin by that point, so he grabbed Sans's arm and pulled him to his feet.

"Enough of this! We're going back to Snowdin!" Papyrus told him.

Papyrus expected his brother to follow him, whether he wanted to or not, but Sans's actual response left him in shock. Sans's left eye glowed, but rather than its normal red, the eye was flashing red and blue. A second later, Sans disappeared from Papyrus's grasp and reappeared a few feet away.

"Wait, what? How did you…?" Papyrus sputtered in confusion, having never seen his brother use his teleportation powers before.

"NO!" Sans denied vehemently. "THIS UNIVERSE IS BROKEN! IT'S BROKEN! IT'S BROKEN! BUT YOU THINK I'M CRAZY! YOU DON'T BELIEVE ME!"

"Sans, I don't have time for whatever this is that you're doing! If you want to play make-believe, play it during your own free time!" Papyrus growled.

"I'M NOT PLAYING! THIS IS REAL! YOU WEREN'T ALWAYS LIKE THIS! BEFORE EVERYTHING WAS BROKEN, YOU WERE A SPAGHETTI-LOVING BALL OF ENERGY, BUT NOW YOU'RE AN ABUSIVE JERK! EVERYONE IS MESSED UP!"

Papyrus was taken aback, more so by the thought that his brother had possibly gone insane than by the accusation. Silently, he decided that, if his brother had snapped, it would be best to act cautiously.

"Okay, Sans, I believe you," lied the skeleton, trying to keep his voice as calm and level as he could. "So, let's go home and figure it out, okay?"

"YOU'RE LYING!" Sans shouted.

Papyrus breathed in deeply to stop himself from yelling again.

"Whether what you're saying is true or not, it will do no good to sit in Waterfall and cry about it," he tried to reason.

Sans paused for a second, seemingly to consider his brother's words, but he quickly shook his head. His eyes flashed again, and he then held a red bone attack in his hand.

"you know, boss, back before the universe broke, I had some reasons not to do this. I had a lot of reasons to do it too, but there was always enough to stop me. and before I remembered what things were like, before I knew just how messed up this universe is, there was never that last little bit that made me do it either. But… now, combining everything from both versions of this universe… I just don't care anymore…," Sans rambled.

Papyrus, realizing what his brother meant by saying "this" started to slowly walk forward as Sans spoke. However, just as he was within arm's reach of the other skeleton, Sans teleported away again.

"isn't it funny, boss? I'm so lazy that I have a power that makes it so I don't have to walk as much…," Sans laughed dryly.

The shorter skeleton prepared to send the bone into his own body. Papyrus stayed silent.

"in the end, this won't even matter, boss. it will all end up resetting eventually. I guess the kid decided to stay in the ruins a bit longer this time," Sans continued. "I can't afford to care anymore."

Right in the second that Sans shot the attack, it was blocked by Papyrus's own attack he had been preparing. Before Sans even registered what was going on, Papyrus hit him with an attack that left him with a risky 0.1 HP and unconscious. Papyrus scooped up his injured brother and trudged back through Waterfall so they could get back to their home.

When Sans woke up a few hours later, his 1 HP fully restored, he found himself locked within a cage of red-orange bones and a collar on his neck. Sans tried to teleport away, but when he couldn't, he realized that the collar must block his magic somehow.

"Sans," Papyrus called out.

The smaller skeleton turned toward the voice and mustered a glare to direct at Papyrus.

"let me out of here, boss," Sans growled.

"Considering the fact that you've clearly gone insane, I doubt that would be a wise decision," Papyrus scoffed.

"I'M NOT CRAZY! the only reason you think I am is because you never remember the resets! BUT I ALWAYS REMEMBER! I only forgot this time because of how messed up the code is!" Sans argued.

"You tried to kill yourself," Papyrus stated simply, despite the fact that he was secretly horrified.

"that doesn't matter! even if I die, that kid will go through the underground and just reset again! I would just get a short break before it starts all over again!" Sans argued. "it'll all just reset again and again and again!"

"ENOUGH, SANS!" Papyrus shouted. "NONE OF THIS STUFF YOU'VE BEEN BABBLING ABOUT IS REAL, AND UNTIL YOU SNAP OUT OF WHATEVER THIS IS, YOU'RE STAYING LOCKED UP!"

"ha, like _you_ actually care!" Sans laughed bitterly.

"I CARE ENOUGH TO KEEP YOU ALIVE! IF I DIDN'T CARE ABOUT YOU, YOU'D BE DEAD, SANS!" Papyrus hollered, accidentally revealing some of his worry.

Sans stared at his brother, clearly shocked by his words.

"I'm not letting you out, Sans," Papyrus told him. "Now, I'm going to have a talk with Undyne, so try to spend some time figuring out reality."

With that, Papyrus left the house in a huff to go find his boss. Considering how late it now was, he easily found her in her some in Waterfall. She wasn't exactly pleased to see the skeleton, but she never really was.

"Why are you here, Papyrus?" she sighed angrily.

"I came to alert you that Sans won't be able to work as a sentry anymore because he has quite literally lost his mind," Papyrus explained.

"For real?" Undyne asked with a long, cruel laugh. "So, what, did he actually kill someone for once?"

"I wish," Papyrus sneered. "That imbecile started going on about all sorts of utter nonsense! He said 'the universe is broken.' It's ridiculous!"

"Well, it's annoying that I'll have to find a new sentry, but I can't have some wacko keeping watch," Undyne grumbled. "Whatever. Get outta here."

With his business complete, the skeleton left the head of the royal guard alone. Once again, he began to make his way back to Snowdin.

Meanwhile, someone else was on the path to Snowdin as well. A young, human child, who was accompanied by a yellow flower, had found themselves in a strangely different world after the last time they reset. Something had gone wrong. Everyone was so much more aggressive and mean. It took forever to actually spare everyone who attacked them. So, considering how hard it had been to traverse the ruins, the child had been expecting even greater resistance on their way to Snowdin. They worried about how Sans would greet them in this corrupted universe, but he never appeared. Papyrus never showed up either, so they just solved the strangely identical puzzles on their own.

"They aren't here…," Frisk mumbled to themself.

The child continued on their way until they stepped into Snowdin. They quickly hid so they could avoid conflict with the town's inhabitants. Cautiously, Frisk and Flowey crept over to the skeletons' house.

"Frisk… I don't like this. What if they see us…?" Flowey complained.

"Sans and Papyrus should have been on the path to Snowdin. After all, I met everyone else in the same places as before," Frisk explained.

The flower sighed, knowing Frisk wouldn't change their mind.

"Don't say I didn't warn you…," Flowey told them.

Their mind made up, Frisk peeked through the window on the first floor. To their surprise, they saw a slightly different version of Sans within the room, trapped within a cage of bones.

"Sans?!" they gasped quietly. "Why is he in a cage?!"

"Frisk, really? With how this world is, is it really that surprising?" Flowey questioned. "His brother probably stuck him in there for whatever reason."

"But… Papyrus wouldn't…," Frisk trailed off.

"The Papyrus _you_ know wouldn't. This one would," Flowey corrected.

Frisk frowned.

"I have to do something," Frisk stated.

Before Flowey could even think to protest, Frisk circled around the house to test all of the windows. Luckily, the lock on one of them was broken, so Frisk could easily open it and crawl inside. After doing so, they quickly went over to the bone cage in the living room.

"Sans?" Frisk called out.

The trapped skeleton's eyes shot up from the floor to Frisk's face.

"…Kid…?" Sans gasped.

"Sans, why are you in here?" Frisk asked.

"heh, well, you know me, kid. I got caught for underCAGE drinking," the skeleton replied.

Frisk giggled, but quickly stopped.

"Come on, you aren't even underage," Frisk pointed out.

"sorry, kid. i'm just not in the mood for jokes," Sans replied. "ya see, I remembered the other timelines before the code got screwed up, and well… now bo-Papyrus thinks I lost it. I was freaking out a bit, so he knocked me out and stuck me in here"

Sans's voice turned into a slight growl at the end.

"Wait. So, you aren't going to try to kill us, then?" Flowey spoke up.

The skeleton glared a bit at the plant.

"let's just say it's a good thing you aren't evil yourself in this universe," Sans answered threateningly.

As Flowey attempted to hide behind Frisk, the child continued their conversation.

"How can I get you out?" Frisk asked.

"can't. these bones aren't gonna disappear until Papyrus makes them, and he put this collar on me to stop me from using magic," he answered. "actually, you should probably get out of here before he gets back."

"I can't just leave you here!" Frisk argued.

Sans sighed.

"look, kid, this universe is broken. things can't stay like this. you need to just keep going and reset," Sans told them.

Frisk was about to argue again, but they heard the sound of a key turning in a lock.

"kid, leave. now!" Sans whispered urgently.

However, it was already too late. The front door swung open and Papyrus stepped in, immediately noticing the human in the room. He paused for a second, letting himself be caught off guard after the hectic day he had experienced due to his brother. He then quickly went into action as he threw a barrage of bones at the child. Frisk was able to dodge a few of them, but the majority hit their mark.

"PAPYRUS, STOP!" Sans shouted when he saw the child get knocked back.

"SILENCE, SANS! I'M TAKING CARE OF THE INTRUDER!" Papyrus shot back.

"THEY'RE OUR FRIEND!" Sans continued when his brother attacked the child again.

Papyrus pinned the human's clothes to the floor with a few bone attacks before turning to Sans.

"SANS, I HAVE HAD ENOUGH OF YOUR DELUSIONS TODAY! HUMANS ARE OUR ENEMIES, AND YOU HAVEN'T EVER EVEN MET THIS HUMAN BEFORE! BE QUIET!" Papyrus ordered angrily.

As the taller skeleton turned back to Frisk, Sans started to slam into the sides of the bone cage.

"PAPYRUS, STOP! YOU CAN'T KILL THEM!" Sans screamed, but to no avail.

Papyrus prepared the attack that he would use to kill the child.

"STOP!" the shorter skeleton yelled in vain.

At their friend's obvious distress, Frisk shakily turned their head toward the skeleton.

"Sans, don't worry. I'll just load my last save point. I'll be fine," Frisk told him, scared of the pain they were about to face, but determined to calm Sans down at least a little. "I'll come back, and I'll get you out. We can fix this-!"

Frisk was cut off as a red-orange bone pierced their stomach.

"FRISK!" both Flowey and Sans screamed.

They stared at the body of the child, neither really understanding why a sight they had both already seen, caused before even, could still affect them so much. However, none of the room's occupants had much time to think about it because the world quickly went back to Frisk's last save point.

Once The child and flower duo made their way back into the skeleton's house again, Sans let out a shaky chuckle.

"geez, kid, I really thought you were _boned_ for a second there. hah…," he spoke. "listen, kid, don't bother trying to get me out this time. it can't be done in time. papyrus will just kill you again."

"But, Sans-!" Frisk was cut off as the skeleton continued speaking.

"kid, please just listen to me this time. you have to get to the end and reset the timeline. then, everything will be fixed, including this. so, don't fight me on this, okay?" Sans continued.

Frisk thought for a second before nodding reluctantly.

"good. now, get outta here," Sans ordered.

That was when they heard the sound of footsteps approaching the door.

"NOW!" Sans shouted urgently.

Frisk quickly scrambled out the window they entered from, not having time to close it. The child sat beneath the window, crouched on the ground. They were out of sight just as the front door swung open and revealed Papyrus once again.

"Sans, why are you yelling?" Papyrus asked.

"well, you think I'm crazy, and crazy people tend to yell a lot, don't they?" Sans shot back.

Papyrus was about to reply with some annoyed remark, but he felt a cold breeze hit him. He turned his eyes to the open window.

"Sans, how did the window open? It was closed when I left," Papyrus asked.

"it was open the whole time. maybe you're the one who's going crazy," Sans retorted.

"What has gotten into you today?" Papyrus hissed.

"I've never met someone who's all rainbows and sunshine after being called crazy and getting locked in a cage," Sans sneered.

"Would you stop being an idiot? You started rambling about things that aren't real and you tried to kill yourself. Most people would call that crazy, Sans," the taller skeleton growled in a repeat of before.

Frisk almost gasped from their hiding place, but managed to keep themself silent.

"it's not my fault that you don't believe me," argued Sans. "in my opinion, the crap you do on a daily basis is a lot crazier than anything I've done today."

"You know I have to do that to toughen you up so you don't die," Papyrus defended himself.

"yeah, tell yourself that," Sans scoffed.

At that, Frisk had heard enough. They carefully crept away from the window to complete their journey.

Before long, Frisk found themself standing in front of the button that would fix this universe. Without hesitation, they placed their hand upon it.

As a child woke up after a nasty fall, a tall skeleton searched for his older brother.

"SANS, WHERE ARE YOU? THERE'S GOING TO BE A HUMAN TODAY! I CAN JUST TELL THAT TODAY'S THE DAY!" Papyrus called out.

Sans stepped out from a tree, his signature grin spread wide across his face.

"don't worry, bo-paps. i'm right here. let's go find that human."

XXX

 _And that's the end. I hope you guys enjoyed reading this cuz it took me a while to write this. :3_


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